Correct Answer - Option 3 : 16

**Given:**

Number of workers in team I = W

Number of workers in team II = W

New number of workers in team I = W - 1

New number of workers in team II = W + 1

**Formula used:**

Total work done = Number of workers × Time taken

**Calculations:**

Total work done by (W - 1) workers in team I = (W - 1)(W + 1)

Total work done by (W + 1) workers in team II = (W + 1)(W + 2)

According to question,

(W - 1)(W + 1)/(W + 1)(W + 2) = 10 : 12

⇒ (W^{2} - 1)/(W^{2} + 3W + 2) = 5 : 6

⇒ 6W^{2} - 6 = 5(W^{2} + 3W + 2)

⇒ 6W^{2} - 6 = 5W^{2} + 15W + 10

⇒ W^{2} - 15W - 16 = 0

⇒ (W - 16)(W + 1) = 0

(W - 16) = 0 or (W + 1) = 0

⇒ W = 16 or (W + 1) = 0

W ≠ -1

So, W = 16.

**∴ The value of W is 16.**